21404471 has 8 divisors (see below), whose sum is σ = 23520000. Its totient is φ = 19317240.

The previous prime is 21404459. The next prime is 21404491. The reversal of 21404471 is 17440412.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21404471 is a prime.

It is a super-3 number, since 3×21404471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21404491) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5471 + ... + 8528.

It is an arithmetic number, because the mean of its divisors is an integer number (2940000).

Almost surely, 2^21404471 is an apocalyptic number.

21404471 is a deficient number, since it is larger than the sum of its proper divisors (2115529).

21404471 is a wasteful number, since it uses less digits than its factorization.

21404471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14149.

The product of its (nonzero) digits is 896, while the sum is 23.

The square root of 21404471 is about 4626.4966227157. The cubic root of 21404471 is about 277.6524433623.

Adding to 21404471 its reverse (17440412), we get a palindrome (38844883).

The spelling of 21404471 in words is "twenty-one million, four hundred four thousand, four hundred seventy-one".